99 Silverado NBS Brake bleeding problem

This is a discussion on 99 Silverado NBS Brake bleeding problem within the Technical / Maintenance forums, part of the General Discussion category; I just replaced all the brake lines on my truck do one leaking and the others looking bad. I am ...

99 Silverado NBS Brake bleeding problem

I just replaced all the brake lines on my truck do one leaking and the others looking bad. I am having a hell of a time trying to bleed the system.
Any tips on bleeding a completely dry brake system? Anyone have any luck with a inexpensive vacuum bleeder?

Re: 99 Silverado NBS Brake bleeding problem

Master, ABS, and lines all dry?
You will want to bench bleed the master if that went dry.
From there keep working at the rest, you should eventually be able to get it to bleed.
Once you are done (may not get a great pedel feel regardless do the following)
Take the truck to a dealer if you have a trusted go there. Have them use the tech II to activate and bleed the abs.

Re: 99 Silverado NBS Brake bleeding problem

Originally Posted by kcb37

Master, ABS, and lines all dry?
You will want to bench bleed the master if that went dry.
From there keep working at the rest, you should eventually be able to get it to bleed.
Once you are done (may not get a great pedel feel regardless do the following)
Take the truck to a dealer if you have a trusted go there. Have them use the tech II to activate and bleed the abs.

Pretty much quick and good advice there.

I did the same work to my truck a while ago and had a heckuva time. But I made it harder on myself by not bench bleeding the master cylinder before then filling the rest of the system. I managed to get enough pedal to brake hard on the sandy road I live on and that cycled the ABS. From there, I kept bleeding but my issue was air trapped in the master cylinder. Thousands of hits with a mallet on the master cylinder later, I got all the air in that to burp out and my pedal got much better. Then, I discovered a few months ago that when I installed the new rear calipers at the time I replaced the lines and hoses, I accidentally installed the calipers on the wrong side, causing the bleeder screws to be lower than the banjo bolt. I corrected that and bled once more and now my brake pedal is back to normal. So, point here is, there are several ways to make this harder and more frustrating that it needs to be, but follow kcb37's steps and you will be setting yourself up for getting a good pedal back sooner than later.

Re: 99 Silverado NBS Brake bleeding problem

Originally Posted by zr900

Can i do a master cylinder bleed while still on the truck? How is this done?

Sure can. If you can get a master cylinder bench bleeding kit for a local NAPA or similar parts store, or take scrap brake lines and route them up and back into the master cylinder reservoir, you can easily bleed the M/C with it in place. I encourage you to search youtube for videos of bench bleeding a M/C as you will quickly understand the concept of how it works and see why removal is not necessary.

The bleeding kit has flexible hoses that come from the two holes at the side of the M/C where the original lines were threaded into. From there, they simply reach up and into the reservoir. From there, you simply fill the reservoir and pump the brake pedal (try not to go all the way to the floor as it may be harsh on the M/C seals) and watch the air bubbles escape. Keep pumping until the air bubbles stop appearing. You should eventually just have fresh fluid cycling through those lines that are going from where the lines come out of the M/C to the reservoir. So long as you don't let the fluid level get too low and allow the M/C to ingest air again, then you will have successfully bled the M/C without having to remove it. If you have the old lines, simply thread them in the two holes on the M/C and bend them up and into the reservoir if you can. The ends of whatever tubes of the kit or salvaged old lines also need to be submerged in the fluid in the reservoir to prevent air from being introduced and undoing you work.

Once that is bled, you will eventually have to take the kit or method you used to bleed the M/C and remove it before you attach the new lines to those two holes on the side of the M/C. This will cause fluid to leak and because brake fluid is highly damaging to paint, you want to sacrifice a cotton towel or shop rags to soak up the dripping fluid and you also want to get those lines attached on there before the fluid level drops far enough to allow air back into the M/C. If the level does get too low, it shouldn't pull air back into the M/C unless you manage to pump the brake pedal. Filling the reservoir up will displace that air back out of the reservoir, but do try to keep that reservoir fluid level up throughout the process if you can.

With all the lines hooked up and tight, they will pull the fluid down from the reservoir so try to keep filling the master cylinder at a rate that prevents air from getting back into the system. If you have a trusty friend/helper, you will want to give them the task of keeping an eye on the level of the fluid in the reservoir and have them fill it as necessary.